Motor speed indicating and control device



Nov. 13, 1934. J. F. BYRD 1,980,907

MOTOR SPEED INDIGATING AND CONTROL DEVICE Filed April 10, 1933 BY 96% QWTOR.

A TTORNEYQY.

Patented Nov. 13, 1934 UNITED STATES PATENT OFFICE MOTOR SPEED INDICATING AND CONTROL DEVICE 3 Claims.

Generically this invention relates to improvements in a tachometer or like device for indicating the engine speed of a motor, but it is more especially applicable for use in connection with airplane motors and adapted to automati- 'cally control a circuit for cutting off the motor when it has attained a predetermined speed.

One of the principal objects of this invention is the provision of means of the above character mounted in the magneto circuit adapted to cause grounding of the magneto and cutting off of the motor when the same attains a predetermined engine speed per hour.

A further important object of this invention is the provision of such device having a stationary dial including a fixed contact and a movable transparent dial superimposed thereon having a movable contact and a switch settable at any desired speed in accordance with the scale carried by the stationary dial, whereby when the indicating hand attains the predetermined setting, the circuit will be closed grounding the magneto and stopping the motor as desired.

With these and other objects in view, which 5 will become apparent as the description proceeds, the invention resides in the construction, "combination and arrangement of parts, hereinafter more fully described and claimed, and illustrated in the accompanying drawing, in which like characters of reference indicate like parts throughout the several figures, of which:

Figure 1 is a top plan view of my improved device showing the predetermined speed setting; Figure 2 is a cross-sectional View taken on the line 2-2 of Figure 1; and

v Figure 3 is a similar View to Figure 1 showing gthe switch carrying dial adjusted to a different position.

Briefly stated, my invention constitutes an improvement in tachometers, preferably in connection with airplane motors and the like, for indicating the speed of rotation of the motor and fincluding an indicating hand and stationary graduated dial and is particularly directed to a fixed contact carried by the stationary dial and a rotatable dial disc superimposed thereon and having a contact adapted to engage said fixed "contact and movable with respect thereto, said 'movable disc also formed with a switch plate in connection with said movable contact, said switch and contact being adjustable with respect to said graduations, whereby when the hand moving in clock-wise direction reaches the predetermined setting and engages said switch, the circuit, through said contacts, will be closed,

thereby effecting stopping of the motor, as will hereinafter more fully appear.

In the illustrated embodiment characterizing this invention, there is shown a tachometer casing A and indicating hand 1 suitably mounted on the upper end of shaft 2, the lower end of said shaft being suitably connected to any well known type of tachometer mechanism (not shown) which in turn is connected with an airplane motor or the like as will be well understood.

The upper edge of casing A is countersunk as at 3 to form a seat for stationary dial 4 suitably secured therein, an electric wire or conductor 5 has one end suitably connected to the magneto (not shown), the other end adapted to extend through dial 4 suitably connected to contact 6 countersunk in the upper surface of said dial as at 7 with its upper surface flush with the surface of said dial.

Superimposed on dial 4 which is constructed of nonconductive material is a transparent dial disc 9 also constructed of nonconductive material and which is mounted on shaft 10 with its lower end suitably mounted within said casing A. Embedded and suitably secured in the undersurface of said disc 9 is a contact ring 11 adapted to movably engage fixed contact 6 and is formed with an arm 12 connected to switch plate 13 formed with an upwardly and out- 85 wardly extending tongue member 14 and with an inwardly extending contact member 15 slightly spaced therefrom. Said switch is adapted to be closed by pointer 1 bridging members 14 and 15 as will hereinafter more fully appear. Said switch plate is suitably secured to dial face disc 9 by rivets 16, one of which connects said switch plate with contact arm 12.

It will thus be seen that the circuit is closed from the magneto (not shown) through conductor 5, stationary contact 6, movable contact ring 11, arm 12, rivet 16, contacts 14 and 15, switch 13, pointer l, and shaft 2 to ground and opened by removal of said pointer from said switch plate as will be clear without further description.

Although the operation of the device would seem to be clear from the above description, it might be well to further state that dial disc 9 may be moved to position switch plate 13 at any desired point with respect to graduations 8, for in- 5 stance, as shown in Figure 1 wherein the indicating hand 1 is shown at full speed position at 15, and should the propellor break or for other reason the engine should be uncontrollably speeded up, when the pointer reaches the position shown 0 in dotted lines at 21, it will close the circuit through switch 13 and cause cutting ofi the ignition and effect stopping of the engine as above explained. Therefore it is apparent that dial disc 9 may be rotated to position switch 13 at any predetermined point with respect to graduations 8 so that when the speed of the engine causes the pointer 1 to reach such predetermined setting, the engine will be stopped.

From the above it is apparent that I have designed a unique adjustable contact means without interfering with the normal function of the dial 4, whereby the stationary and movable contacts may be adjustably positioned with respect to each other so as to automatically effect cutting off of the ignition and consequent stopping of the motor when the same has attained any predetermined speed, and which mechanism may be expeditiously applied to different types of tachometers without material alteration, or said devices may be so equipped in the first instance .at a minimum cost, such improved devices being positive in operation, expeditiously adjustable, manufacturable at a minimum cost, pleasing in appearance, simple in design, and efiicient for the purposes intended.

Though I have preferably shown my improved adjustable circuit opening and closing means as applied to airplane motors, it is to be understood that the same is adaptable to a variety of uses and susceptible of application in connection with other types of indicating or measuring devices as desired.

Although in practice I have found that the form of my invention illustrated in the accompanying drawing and referred to in the above description as the preferred embodiment is the most efiicient and practical; yet realizing the conditions concurrent with'the adoption of my invention will necessarily vary, I desire to emphasize that various minor changes in details of construction, proportion and arrangement of parts, may be resorted to within'the scope of the appended claims without departing from or sacrificing any of the principles of this invention.

Having thus described my invention, what I desire protected by Letters Patent is as set forth in the following claims:

1. A circuit control device including an indicating pointer, and a fixed insulated dial bearing suitable graduations on its face, a stationary contact carried by the dial, a rotatable transparent insulated disc mounted in superimposed relation with respect to said dial, said disk being formed with a seat in which is positioned a movable ring contact for continuous engagement 7 with said stationary contact irrespective of the movement of said disc, and means connected to said ring contact engageable with said pointer, whereby closing of the circuit is effected.

2. A circuit control device including an indicating pointer carried by a shaft, a fixed insulated dial bearing graduations on its face, a stationary contact carried by the dial flange with the plane surface thereof, a rotatable relation with respect to said dial and formed on one surface with a ring contact, a pair of normally open contacts mounted on the opposite surface of said disc connected to said ring contact and predeterminedly adjustable with respect to said graduations, whereby when the pointer reaches such setting the circuit will be closed.

3. A circuit closing. device including an indicating pointer carried by a shaft for actuating the pointer, in combination with a fixed insulated 105 dial. bearing graduations on its face, a contact carried by the dial,-a transparent insulated disc rotatably superimposed on said dial and formed with a contact member engageable with said fixed contact irrespective of the movement of said lid disc, and pointer engageable means carried by said disc connected to said member, said means being predeterminedly adjustable with respect to said graduations, by said disc, whereby when said pointer engages said means closing of the circuit 115 is effected.

JOHN F. BYRD. 

